It has been brought to light that in general, pollen grains, though varying depending on the kind or the growing environment, etc. of the flowers, contain abundantly a number of effective ingredients that are indispensable to the life maintenance of living bodies such as proteins, sugars, vitamins, minerals, various amino acids, etc. Recently, therefore, these pollen grains are being utilized as the highly nutritious natural foods containing well-balanced nutrients, and the method of processing also gradually changed to those which can provide safer foods and are more advantageous. Commercially, a number of marketable articles have appeared before the foot lights by utilizing the pollen grains or "pollen load" (i.e., pollen grains made into the form of small balls by honey-bees when they carry the pollen grains to their nest) processed into a variety of forms such as powder, granules, particles, etc, as cosmetics, foods, etc.
The formation of pollen takes place in such a manner that the pollen-mother-cell first formed in the anther of a flower forms four cells, i.e., pollen tetrad by a process of reduction division, and then each cell of the pollen tetrad individually grows storing up reserves such as starch. Said anther is full of a liquid, and it is said that the nutiritious ingredients in the pollen are formed in this liquid. It is also known that when the pollen begins to be formed, the adjacent cells in the pollen-mother-cell are partitioned by a cell membrane formed of lipoprotein, etc., but onto the outside of said cell membrane sporopollenin or the like substance and onto the inside of said cell membrane pectin or the like substance gradually adhere and form the outer and inner walls. As said inner wall is equivalent to the cell membrane of the ordinary cell, it follows that the pollen is enveloped not only with the cell wall but also with one more outer wall. The pollen thus enveloped with mantle membrane consisting of these inner and outer walls puts on oily substance or coloring matter, etc. around itself before the flowering and comes out from the flower at the time of flowering. The outer wall of said pollen also contains lignin in addition to the above described sporopollenin, the inner wall which forms the cell wall contains cellulose in addition to the above described pectin, the cell membrane contains lipids and proteins, and the interior of the cell wall contains abundantly a great many effective ingredients such as starch grains, lipid particles, etc.
However, the sporopollenin which is found in the outer wall of said pollen is so tough and stable a substance that it is very difficult to decompose even by acid, alkali, or enzyme, and as said pollen is a highly active living body which can stand the changes in its chemical and physical environments to such an extent that said pollen is considerably resistant to heat, and stable enough to remain unchanged when immersed in an organic solvent such as ether, alcohol, etc., or can extend its pollen tube even under the irradiation with radiant rays, a serious problem arises as follows. That is, even if said pollen could be incorporated as such into any foodstuff, it is either eliminated without any decomposition or only slightly decomposed through the germ pore of the pollen, so that the greater part of the effective ingredients can be neither digested nor absorbed.
In an attempt to overcome the above described problem a process wherein pollen is germinated in an artificial culture using cane sugar solution, etc., or pollen is triturated in a mortar after it has been subjected to enzyme treatment was devised, but in the former process it is almost infeasible for the following reasons. That is, since the properties of pollen greatly differ depending on the kind of the plant, in some cases no pollen can be germinated absolutely in an artificial culture, and since the optimum concentration of cane sugar is also quite specific to the pollen, not only does it happen that when said concentration is either too high or too low no pollen is germinated, but also the time required for the pollen to be germinated is so much widely different that it varies from 2 minutes in garden balsam to 20 hours in Japanese red pine. On the other hand, in the latter case, although the trituration can be achieved to the extent of about 50% complete, there is a defect that the operation requires a long period of time.
In order to overcome the above described problems hitherto known the present applicant provided "a process for extracting contents from pollen grains by crushing the cell membrane of said pollen grains which comprises keeping pollen grains irrespective of the kind thereof for more than 24 hours in a freezer at -20.degree. C., and then putting said pollen grains into a mixer bowl while rapidly pouring hot water at 90.degree.-100.degree. C. on said pollen grains in a proportion of hot water:pollen=200 ml:5 g, followed by stirring" [Japanese Patent No. 1002326 (Japanese Patent Publication No. 31067/1979)], but in this process it was intended to extract contents from pollen grains by crushing the cell membrane, but not the mantle membrane of the pollen grains, so that the complete extraction of contents could be hardly achieved, and moreover, because of the hot water being used there was a fear of destroying the thermolabile ingredients among the effective ingredients of the pollen grains.